Mako Vunipola will start at loosehead prop for England against Italy in place of Joe Marler Photograph: David Rogers/Getty Images

Mako Vunipola has been drafted in to start at loosehead prop in England's final Six Nations championship game against Italy after Joe Marler's partner went into labour.

The Harlequins forward Marler did not fly out to Rome with the rest of England squad on Thursday, so as to attend the birth of his first child, and the Rugby Football Union confirmed on Thursday night that Saracens' Vunipola would be promoted to the starting XV, with Matt Mullan of London Wasps taking his place on the bench.

"It is important that Joe is with his partner at this exciting time," said England's head coach, Stuart Lancaster. "Family must always come first and everyone in the squad wishes them well. We have prepared for being without Joe and we have no doubt Mako will slot straight in and perform, as will Matt Mullan should he get an opportunity.

"Matt played in the autumn internationals. There's no problem with him; he's been involved right throughout the campaign. He's a good player to come on."

The Leicester back Manu Tuilagi will also be on the bench after being confirmed in an England squad for the first time in a year. An operation to repair a torn pectoral muscle has meant he has not represented his country since the defeat by Wales in Cardiff last year and he is itching to make up for lost time. "It's been a tough five or six months for me just watching from the touchline. Especially given the way the boys are playing, you want to be part of the team. It's going to take a lot of work for me to get back in to the starting XV."

His role against Italy may well be as a second-half wing replacement as England seek the high-scoring win which could boost their chances of lifting the title. Tuilagi played his age-group rugby on the wing and Lancaster believes he is quick enough to play there at senior level if required. He has warned, nevertheless, against expecting instant miracles from the 22-year-old. "He can definitely make an impact but I don't want to raise expectations that you bring Manu on and he'll suddenly score four tries. He played against Italy last year and didn't score any."

England, collectively, have struggled to score tries against Italy in recent seasons and Lancaster has stressed the need to build significant first-half pressure to have any chance of cracking open their hosts' defence later on. "I have impressed on the players the need to play with the same sort of intensity and tempo and intent we showed against Wales. You've got to be patient and build a score."

With Ireland and France kicking off in Paris later in the day, England will have no idea precisely how many points they ideally need to score in Rome. Lancaster does not think it will matter greatly, having long been a believer that the scoreboard looks after itself if a team perform well enough. "It's irrelevant whether we kick off at the same time or later because we've still got to play well. We went into the final game last year [against Wales] knowing what we had to do and it didn't help at all."

Italy, meanwhile, will be without the injured Martin Castrogiovanni but their inspirational Sergio Parisse is back at No8. Lorenzo Cittadini starts at tighthead in place of Castrogiovanni, with loosehead Matías Agüero replacing Alberto De Marchi, but it is Parisse who is concentrating most English minds. "He's a talisman for them," Lancaster said. "It's like playing three extra players when he's playing."

The Rugby Football Union has put in place new standards for the length of time that concussed players must serve before they are allowed to return to play. Professional players will now be sidelined for six days, while elite age-group players between U17 and U19 cannot return for 12 days. At grassroots level the routine minimum stand-down period will be 19 days for adults and 23 days for U19 players.